Both an oxide thin film transistor (TFT) and an amorphous silicon TFT could be used as a driving element in display panels such as an organic light-emitting diode (OLED) display panel, a polymer light-emitting diode (PLED) display panel and the like. The carrier concentration in the oxide TFT is larger than that in the amorphous silicon TFT by 10 times. In addition, the oxide TFT may be manufactured by a magnetron sputtering method, so it is not needed to greatly change conventional production lines of the liquid crystal display panel upon adopting the oxide TFT. At the same time, as there is no limit caused by equipments used in the processes of ion implantation, laser crystallization and the like, the oxide TFT is more suitable for large-area display panels compared with a polysilicon TFT.
FIG. 1 is a structural schematic view illustrating a conventional oxide thin film transistor, which has a bottom gate. The manufacturing process of the oxide TFT is provided as follows: depositing a gate metal layer on a glass substrate 110, and forming a gate electrode 120 by an etching process; depositing a gate insulating layer 130 and an oxide semiconductor layer which may be formed by indium gallium zinc oxide (IGZO), and wet-etching the oxide semiconductor layer to form an active layer 140; depositing a SiOx (silicon oxide) layer, and forming an etch barrier layer 150 by an etching process; and finally forming a source electrode 160 and a drain electrode 170.
In the above manufacturing process, gas molecules in the reaction atmosphere enter into a plasma and are decomposed into charged ions during the process of forming the etch barrier layer of SiOx. These charged ions have high energy and may generate a bombardment effect when they are jetted to the substrate by the plasma. This may form defects on the surface of the IGZO thin film that has been formed on the substrate, and in this case, the performance of the oxide TFT may be deteriorated. In addition, it cannot efficiently prevent the water vapor from diffusing into the active layer 140 in the case of adopting SiOx to form the etch barrier layer, and in this case, the performance of the oxide TFT may be further deteriorated. In addition, the SiOx thin film is generally deposited by using a chemical vapor deposition (CVD) apparatus, and such apparatus is expensive and huge and has high energy consumption.